The invention provides a die for molding by a double-layered helical tooth demolding mechanism, and belongs to the technical field of plastic dies. The die is characterized in that a fixed die rack 401 is driven by a fixed mold wedge 402 to do rectilinear motion; a fixed die gear 105 is driven by the fixed die rack 401 to do circular motion; an outer ring fixed die rotary tooth 101 is driven by the fixed die gear 105 to rotate in an outer ring fixed die helical casing 104 through a helical line and do radial motion, so that fixed die double-layered tooth part of a product 500 is separated; a movable die rack 301 is driven by a movable die wedge 302 to do rectilinear motion; a movable die gear 205 is driven by the movable die rack 301 to do circular motion; and an outer ring movable die rotary tooth 201 is driven by the movable die gear 205 to rotate in an outer ring movable die helical casing 204 through a helical line and do radial motion, so that the movable die double-layered tooth part of the product 500 is separated. The die overcomes the defect of passive demolding, and ensures the precision and the tolerance of the product, since an active demolding way is adopted, the possibility that the product is pulled due to passive demolding is reduced, the molding cycles of the product are shortened, and the productivity of the product is improved.